The equation y=36x is a linear equation and you can graph it by giving different numbers to the X in this example you have toput the different numbers of the X in the equation:
so you´d have to do is:
Y= 36(0.5)= 18
Y= 36(2)= 72
Y= 36(3)= 108
Y= 36(6)= 216
You can now affirm that the graph that correctly describe the proportional relationship is the third one.